Thread trimmer for sewing machines



1,483,308 J. KIEWICZ THREAD TRIMMER FOR SEWING MACHINES Een. 12, 1924;

Filed Sept. 27`. 1922 G'Sheets-Sheec 2 lll lll.. IIL

Feb. 12 1924.."-

. J. KIEWICZ THREAD TRIMMER FOR SEWING MACHINES Filed sept. 2v, esheets-snai Figli lnvenor. John Kewic? Feb. 12,1924. 1,483,308

y J.,KIEWICZ v THREAD 'lRIMMER FOR SEWING `MACHINES v Filed Sept. 27,1922 6 Sheets-Sheet, 5

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nvenTov Feb. l2, 1924.

' 1,483,308 J. KlEwlcz N THREAD TRIMMER Fon SEWING MACHINES `Filed Sept.27. 1922 6 Sheets-sheet 6 Patented Feb. l2, i924.

NET STATES PATENT FFECE.

JOHN KEWICZ, 0F BOSTON, MASSACHUSETTS, ASSIG-NOR TO THE REECE BUTTONHOLE MACHINE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION 0F MAINE.

THREAD TRIMMER FOR SEWING :MACHINES Application filed September 27,1922. Serial No. 590,973.

T o all whom t may concern:

Be it known that l, JOHN l'inwicz, a citizen of the United States, andresident of Boston, county of Suffolk, State of Massachusetts, haveinvented an Improvement in Thread rTrimmers for Sewing Machines, ofwhich the following description, in connection with the accompanyingdrawings, is a specification, like characters on the drawingsrepresenting like parts.

This invention relates to sewing machines of the type adapted to sew ashort seam and then come to rest, and it has particular reference temeans for trimming the under thread beneath the throat plate at the endof each seam.

The invention is in the nature of an improvement on the thread-trimmingdevice illustrated in my co-pending application Ser. No. 552,926, filedApril 15, 1922. The sewing machine shown in said application is providedwith the usual loose pulley and a fast pulley, the 'driving belt beingshifted from the loose pulley to the fast pulley to operate the machineand being returned to the loose pulley when the machine is stopped. Insaid application the thread cutter isactuated from the loose pulley whenthe belt is shifted from the fast pulley to said loose. pulley at thecompletion of the yseam and one feature of my present invention relatesto an improved mechanism for actuating the thread cutter from the loosepulley Another feature of the invention relates to an improved form ofthread cutter which is o f that type that operates first to pull off alength of the under thread from the shuttle and then to sever saidthread close to the work.

In order to give an understanding of the invention I have illustra-tedin the drawings a selected embodiment thereof which will now bedescribed after which t-he novel features will be pointed out in theappended claims.

In the drawings, Fig. 1 is a side view of a sewing mach-ine embodying myinvention.y

. Fig. 2 is an end view.

Fig. 3 is a top plan view of the portion of the cutter actuatingmechanism .which is associated with the loose pulley. y

Fig. 4 is an under-side view of the sewing machine bed frameillustrating the position of the under thread cutter.

Fig.. 5 is a plan vier7 of the removable plate of the bed frame to whichthe under thread cutter is secured.

Figs. 6, 7 and 8 are under side views thereof showing the parts indiiferent positions.

Fig. 9 is a section on the line 9 9, Fig. 8.

Fig. 10 is a detail view of the latch for holding the pin 48 elevated.

The sewing machine herein illustrated comprises the bed 1 which ispivotally supported on a base 2 vand. which carries the overhanging arm3 that supports the vertically-reciprocating needle bar 4, the lattercarrying the usual -upper needle 5.

The sewing machine is a two-thread sewing machine and the under threadis taken from a bobbin carried by a bobbin carrier situated beneath thebed plate 1 and during the formation of each stitch a loop of needlethread is carried around the bobbin carrier by means of a rotary hookall as usual in two-thread sewing machines. The bobbin carrier androtaryhook are not illustrated in detail as they may have any suitable orusual construction but are shown generally at 6. Both the upper needleand the rotary hook are actuated from a driving shaft 7 by any suitablemechanism, which it is not necessary to describeherein, and said shafthas fast thereon a fast pulley 8 by which it is driven. Associated withthe fast pulley 8 is a loose pulley 9 over which the driving belt 10passes when the-machine is at rest.

To start the machine the driving belt 10 is shifted to the fast pulley8, andwhen the machine is stopped again it is shipped back onto theloose :pullep 9. The belt is shifted from one pulleyto the other by abelt shipper .indicated at 11 which is carried by the end of an arm 12extending from a bracket 13 forming part of the stop mot-ion. Thisbracket is carried by a rock shaft 14 which is mounted in the bed frameso that it can turn and also is arranged to have a movevment in the.direction of its length, the latter movement being `that which shiftsthe belt from one pulley toy the other. This bracket arm 13 forms partofthe stop motion which brings the. machine to rest at the end of thestitc'ahing'y operation and when lil the machine is in operation saidbracket arm is in the dotted line position FigA This bracket arm 13 hasa stop dog 15 which co-operates with a stop cam 16 fast on the driving`shaft 7 for bringing the machine to rest at the end of the seam. Whenthe macliine'is running and the bracket arm 13 is in the dotted lineposition the stop dog 15 is on the inside of the stop cam 16 and is freetherefrom. At the end of the sewing operation the trip or catch holdingvthe stopmotion in its inoperative position is released and the rockshaft 14 and bracket arm 13 are moved into the full line position Fig; 3thus bringing the stop dog 15 into engagement with the stop cam 16. Thisstop cam has the rise 17, the valley 18 beyond the rise and the stopface 19 beyond the valley. The stop cam is rotating anti-clockwise Fig.2 and when the stop dog is shifted into engagement with the cam at theend of the seam the high portion 17 of the cam will pass under ksaidstop dog and the latter will then drop into the valley 18 and be engagedby the stop face 19. The bracket arm 13 is acted on by a spring-pressedplunger 2O which resists upward movement thereof and thus applies abraking pressure while the high portion 17 of the stop'cam is passingunder the stop dog. Said stop dog is carried by a plunger 21 slidablymounted in the bracket 13 and actedon by a spring 22 which is compressedwhen the stop face 19 `engages the stop dog thus bringing the parts torest with a cushioned movement.

The parts thus far described are or may be all as usual in driving andstop mechanism of this type and form no part of my present invention. Infact the mechanism thus far described is substantially the same as isillustrated in my above-mentioned co- `pending application.

The work in which the seam is to be sewed (which in the present instanceis the stitching on a buttonhole) is retained on a clamp plate 25 bymeans of usual work clamps 26.

The cutting device for trimming the under thread comprises a pull-offmember 23 situated'beneath the clamp plate 25 and pivoted thereto at 24and adapted to act on the under thread 27 at the end of the seam to drawoff a length thereof, and a cutting member 28 also pivoted to the clampplate 25 at 29 and having a cutting edge30 which is carried against theythread to trim the latter close to the work. y

The pull-oft' device and cutting member normally occupy the positions`shown in Figs. 5 and 6, the pull-off member being retained in this`position by a spring 31 and the knife by a spring 32. These lmembersare actuated at the end of each seam by `meansfof an actuator v3 3 inlthe vform of a `Arod which `is vsldably sustainedl 'by the bed 1, andthe rod in turn is actuated by the loose pulley 9 after the belt isshifted from the fast to the loose pulley.

The actuator 33 is provided with an arm 34 having a notch 35 and thepull-olf member 23 andcutter 28 are provided with cam ribs 36 and 37which are adapted to be engaged by the walls 38 of the notch when theactuator moves from the position shown in Fig. 6 to that shown in Fig.8. The engagement of the walls of the notch with the ribs causes thepull-off 23 and cutter 28 to be swung inwardly7 the inward movement ofthe pull-ofi' operating to pull off a length of the under thread 27 andthe inward movement of the cutter operating to sever said thread.

The arrangement is such that when the actuator is given its operativemovement it will first actuate the pull-ofi'l member to pull off alength of thread and will subsequently operate the cutter to sever thethread. The rib 36 is considerably longer than the rib 37 and is sosituated that when the arm 34 has its operative movement from the dottedline position Fig. 6 into the full line position Fig. 8, said arm firstengages the cam rib 36 and swings the pull-ott member 23 inwardly intothe position shown in Fig. 7, and then one wall 38 of the notch engagesthe cam rib 37 and actuates the cutter thereby carrying it into theposition shown in Fig. 8 and severing the under thread.

The rib 36 is slabbed ofl' as shown at 40 so that when the pull-ofi'member 23 has been swung into its operative position shown in Fig. 7this slabbed-ofi' face stands parallel to the direction of movement ofthe arm 34 and, therefore, during the time that the cutter 28 isoperating the pull-off member will be stationary.

The arm 34 and actuator 33 are normally retained in their inoperativeposition by means of a spring 41.

As stated above the movement of the actuator 33 is derived from theloose pulley 9 after the driving belt 10 has been shifted onto it whenthe machine comes to rest and the mechanism for accomplishing this,while somewhat similar to that shown in my copending application Ser.No. 552,926 is, nevertheless, an improvement thereon.

The bed 1 has a rod 42 slidably mounted therein and said rod carries aforked block 43, the arms of which embrace a lever 44 piv oted to thebed at 45. The outer end of this lever extends under the actuator 33 andthe end of the latter is bent downwardly as shown at 46 so that swingingmovement of the lever 44 from the full to the dotted line position Fig.3, due to longitudinal movement of the rod 42, Awill give the operativemovement to the actuator 33.

The rod 4 2 has fast thereon a bracket 47, and the latter sustains a pin43 which is 7 arm and cutter.

vertically movable therein and when in lowered position is adapted tocouple said bracket to a worm 49 that is fast to the loose pulley 9. Thepin 48 is normally held in its elevated position out of engagement withthe worm 49 by means of a latch 50, the end of which engages under ahead 51 formed on the pin. Said pin is acted on by a spring 52 tendingto move it downwardly.

During the stitching of the buttonhole the clutching pin 48 is retainedin its elevated position by the latch 50 which is pivoted to the bracket47 at 61 and is acted upon by a spring 54, and as the machine comes torest at the end of a seam and the belt is shifted to the loose pulley 9the latch 50 is released from the head 51 of the clutch pin and thelatter is forced downwardly by its spring 52 into engagement with theworm 49. The rotation of the worm operates through the clutch pin tomove the bracket and the rod 42 to the right in Fig. 1 or downwardly inFig. 3 thus giving the movement to the lever 44 and actuator 33necessary to operate the pull-ofi" As the pin 48 reaches the end of theworm it is automatically disengaged therefrom and this is provided forby making the worm with. the cam surface 53 which by its engagement withthe endof the pin :torcesthe latter upwardly out of` en# gagei'nent withthe worm groove. As soon as the pin has been -raised suiticiently thelatch. 50, which is acted upon by the spring 54, snaps in under the head51 and holds the pin raised, and the spring 55, which is connected to anarm 86 depending from the rod 42 restores the parts to the positionshown in Fig. 3.

The releasing of the latch 50 from the head of the pin 51 is hereinderived from the cushioning` movement which the clutch dog 15 has whenit engages the stop face 19 of the stop cam at the time that the machineis brought to rest. The shank 21 of this clutch dog is provided with ablock 56 adapted to engage one end of a lever 57 pivoted to the bracket47 at 58, the other end 59 of the lever bearing against the end 60 ofthe latch 50. After the clutch dog 15 drops into the valley 18 theengagement of the stop face 19 with the clutch dog moves the latter tothe left Fig. 2 against the action oi the spring 22 thus giving thecushioned stopping movement. This slight movement of the clutch dogcauses the block 56 to engage the end of the latch-releasing lever 57thereby giving it operative movement to release the latch 50 from thehead of the pin and as soon as the pin is released it is carried intooperative engagement with the worm by the spring 52 as above described.

The latch-releasing lever 5,7 and the latch 50 are shown as connected bya spring 63 which not only maintains'them in engagement but also servesto hold the free end of the lever 57 in the position shown in Fig. 3, inwhich position it is out of the path of movement ci: the block 56 as thebracket arm 13 moves from the'dotted to the full line position Fig. 3.

I claim:

1. In a sewing machine, the combination with work-holding means, of apivoted pulloff arm situated beneath the work and hav ing a cam rib, apivoted cutter also situated beneath the work and having a cam rib, andan actuator having a forked portion to engage said ribs and thus givesaid elements their operative move-ment.

2. In a sewing machine, the combination with work-holding means, of apivoted pulloif arm situated beneath the work and having a cam rib, apivoted cutter also situated beneath the work and having a cam rib, andan actuator having a forked portion to engage said ribs, the latterhaving such a relative position that during the movement of the actuatorit operates first the pull-oil' arm and then the cutter.

3. Ineu sewing machine, the combination with work-holding means, of apivoted pulloff arm situated beneath the work and having a cam rib, apivoted cutter also situated beneath the work and having a cam rib, andan actuatoradapted to engage said ribs, the latter having such arelative position that during the movement ofthe actuator it operatesfirst the pull-oli' arm and holds it in pulling-oli' position andthenoperates the cutter."

4. In a sewing machine, the combination with work-holding means, of` apivoted pullolf arm situated beneath the work and having a cam rib, acutter also situated beneath the work and having a cam rib, a slidablerod having a forked portion to engage said ribs thereby to actuate thepull-oil and cutter.

5. In a sewing machine, the combination with work-holding means, of apivoted pulloit' arm situated beneath the work and having a cam rib, acutter also situated beneath the Work and having a cam rib, a slidablerod having a forked portion to engage said ribs thereby to actua-te thepull-off 4and cutter, the rib on the pull-off being longer than the ribon the cutter whereby the pull-off is actuated first and then the cutteris actuated.

6. In a sewing machine, the combination with work-holding means, of apivoted pulloi' arm situated beneath the work and having a cam rib, apivoted cutter also situated beneath the work and having a cam rib, anactuator adapted to engage said ribs and give said pull-oil' and cuttertheir operative movements, a driving mechanism for the sewing machinecomprising a driving belt, a fast pulley from which the machine isoperated and a loose pulley, means to shift the belt from the tast tothe loose pulley at the end of the sewing operation, and means actuatedby the loose pulley to give movement to said actuator.

7. In a sewing machine, the combination with work-holding means, of apivoted pullof arm situated beneath the Work and having a cam rib, apivoted cutter also situated beneath the work kand having a cam rib, anactuator adapted to engage said ribs andv thus give said elements theiroperative movement, a driving elementv for operating the machine, meansto connect said driving element to or disconnect it from the machine,and means actuated by the driving element after it is disconnected fromthe machine to give movement to the actuator.

8. In a sewing machine having a fast pulley, a loose pulley, al drivingbelt for said pulleys, and a stop motion including a belt shipper and acushioned stop dog, the combination with said loose pulley 'and stopdog, of a worm fast to the loose pulley, a member normally disconnectedfrom the worm, means controlled by the cushioning movement of the stopdog to connect said member to the worm, and a'thread cutter actuated bysaid member.

9. In a sewing machine having a fast pulley, a loose pulley, a drivingbelt for said pulleys and a stop motion including a belt shipper and acushioned stop dog, the combination with said loose pulley and stop dog,of a worm fast to the loose pulley, a member normally disconnected fromthe worm, means controlled by the cushioning movement of the stopl dogto connect said member to the Worm, and a pull-off and thread cutteractuated by said member.

l0. In a sewing machine having a fast pulley, a loose pulley, a drivingbelt for said pulleys and a stop motionv including a belt shipper and acushioned stop dog, the combination with said loose pulley and stop dog,of a worm fast to the loose pulley, a slidable member normallydisconnected from said Worm, a clutch pin for connecting the member tothe worm, a latch holding the clutch pin inoperative, means actuated bythe cushioning movement of the sto-p dog to release the latch and acutter actuated by said slidable member.

11. In a sewing machine having a fast pulley, a loose pulley, a drivingbelt for said pulleys and a stop motion including a belt shipper and acushioned stop dog, the combination with said loose pulley and stop dog,'of a worm fast to the loose pulley, a slidable member normallydisconnected from said worm7 a clutch pin for connecting the member tothe Worm, a latch holding the clutch pin inoperative, means actuated bythe cushioning movement of the stop dog to release the latch and athread .pull-off and cutter actuated by said slidable member.

In testimony whereof, I have signed my name to this specification.

JHN KIEWICZ.

